A railway vehicle generally includes several motors of this type, positioned on the bogies and driving the wheels. To do this, the electric motors transform into a rotary movement electric power produced by the generator of the vehicle or directly provided from a power supply cable.
These motors generally consist of a rotary portion, the rotor, and a fixed portion, the stator, attached in a stator frame which plays a role for protecting and insulating the motor and receives a circuit for cooling the motor.
The frame is a metal casing, generally in an iron alloy for maximum mechanical strength, for example in cast iron or in steel. Several methods for manufacturing such a motor frame are known.
A first method consists of molding the frame in a single part, generally in cast iron, which has advantages notably in terms of cost. Further, a frame in a single piece is more rigid and solid. However, the thereby obtained frame is heavy and bulky.
In order to reduce the mass of the frame, it is known how to use a structure of several parts welded together, notably comprising two end plates connected with parallel bars. In order to compensate for the lower resistance of such a structure, steel is generally used for all the parts, which gives the possibility of welding the parts with each other, but substantially increasing the cost of the manufacturing of the frame. Further, a frame consisting of several welded parts may be subject to distortions under the effect of internal stresses generated by the cooling of the welding areas. These distortions may be reflected on the stator, which may be detrimental to proper operation of the electric motor by forming hot spots or a magnetic unbalance.
An object of the invention is to provide a motor stator frame which is more resistant to distortions and less expensive, while having a reduced bulkiness.